Anticoagulation challenges in patients with hematological malignancy-associated thrombosis and severe thrombocytopenia

Patients with cancer are at increased risk of venous thromboembolism (VTE), with incidence rates of 5-20% depending on tumor type, stage, and treatment. The coexistence of cancer-associated thrombosis (CAT) and thrombocytopenia is a particularly challenging therapeutic dilemma, occurring in nearly half of patients with hematologic malignancies and in about one-fifth of patients with solid tumors who require anticoagulation. This review looks at the most recent research on how to manage anticoagulation in people with hematological malignancy-associated thrombosis and severe thrombocytopenia (a platelet count of less than 50×10⁹/L). Robust data are limited because pivotal trials systematically excluded patients with moderate-to-severe thrombocytopenia when establishing the standard of care for CAT treatment. The existing evidence largely comes from small retrospective studies and only three prospective observational studies, which predominantly enrolled patients with hematologic cancers. These studies demonstrate variability in clinical practice encompassing full-intensity anticoagulation with platelet transfusion support, reduced-dose regimens, and treatment interruption. Major bleeding rates ranged from 3% to 13%, while VTE recurrence occurred in 0% to 6% of cases across different management approaches. Current guidelines generally agree on the need for personalized treatment decisions guided by VTE severity, bleeding risk assessment, and platelet count trajectory. However, platelet counts alone demonstrate poor predictive value for bleeding events, and maintaining platelet counts above 50×10⁹/L through transfusion does not consistently prevent hemorrhagic complications. Optimal management requires tailored, multidisciplinary approaches. The forthcoming START trial will compare the efficacy of dose-adjusted anticoagulation versus transfusion-supported full-dose therapy, which could establish an evidence-based standard of care for this vulnerable population.